[Fix] Update mmcv and markdown dependency version

[Ben-Louis]

Motivation

Update mmcv maximum version from 1.6.0 to 1.7.0

Modification

Update mmcv maximum version in

• mmpose/__init__.py
• FAQ

BC-breaking (Optional)

Use cases (Optional)

Checklist

Before PR:

• I have read and followed the workflow indicated in the CONTRIBUTING.md to create this PR.
• Pre-commit or linting tools indicated in CONTRIBUTING.md are used to fix the potential lint issues.
• Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
• New functionalities are covered by complete unit tests. If not, please add more unit tests to ensure correctness.
• The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• CLA has been signed and all committers have signed the CLA in this PR.

[codecov]

Codecov Report

Merging #1516 (ff1d125) into master (fc0b7e6) will increase coverage by 0.00%.
The diff coverage is 80.00%.

❗ Current head ff1d125 differs from pull request most recent head 2c60830. Consider uploading reports for the commit 2c60830 to get more accurate results

@@           Coverage Diff           @@
##           master    #1516   +/-   ##
=======================================
  Coverage   84.45%   84.46%           
=======================================
  Files         236      236           
  Lines       20038    20039    +1     
  Branches     3603     3603           
=======================================
+ Hits        16924    16925    +1     
  Misses       2233     2233           
  Partials      881      881           

Flag	Coverage Δ
unittests	84.36% <80.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmpose/apis/inference_tracking.py	61.71% <75.00%> (+0.30%)	⬆️
mmpose/__init__.py	70.58% <100.00%> (ø)

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